ShorelineCalc v1.5

Location & Coastline

GPS Position

Latitude

Longitude

Paste latitude, longitude

Ready. Default example: Cambridge.

Coastline Data

Online dataset

Coastline loads automatically on first calculation.

Natural Earth is general mapping data and is not a legal mean high-water boundary.

Shore Distance Result

Minimum straight-line distance to mapped coastline

—

Miles—

Nearest shore lat/lon—

Bearing to shore—

Segments checked—

Dataset—

Directional Shoreline Distances

Directions are measured clockwise from due north and represent the upwind wind-from direction. The first coastline crossing along each 30° ray is reported.

Clockwise from Ndegrees	Distance to shorelinekm	C_dirUK NA Table NA.1

Select a UK map location or calculate the entered coordinates.

Fundamental Basic Wind Velocity

Figure NA.1 value before altitude correction

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OS easting—

OS northing—

Grid reference—

Value source—

Estimated map reading—

Click a location on the map or calculate the entered coordinates.

Figure NA.1 Overlay

Show supplied wind-map isopleths Overlay opacity

Manual v_b,map override (m/s)

The displayed value is digitised and interpolated from the supplied Figure NA.1 isopleths. Use the manual override where the original code map is read differently.

Basic Wind Velocity

Site altitude A (m)

Reference height z (m)

Wind direction FROM (°N)

Season factor c_season

Return period T (years)

Altitude factor c_alt—

Directional factor c_dir—

Probability factor c_prob—

Fundamental velocity v_b,0—

Basic velocity v_b—

Basic pressure q_b—

q_b is the basic velocity pressure only. Peak velocity pressure and final wind force still require terrain/exposure, orography, structural and pressure/force coefficients.

Upwind Obstructions

Average adjacent-building height h_ave (m)

Upwind spacing x (m)

Displacement height h_dis0.00 m

For town terrain, h_dis follows EN 1991-1-4 Annex A.5. The exposure-chart height is z − h_dis, with a minimum value of 2 m.

Exposure Factors

Terrain

Country Town

Country exposure factor c_e(z)—

Town correction c_e,T1.000

Orography factor c_o1.000

NA.4a bracket1.000

Peak velocity pressure q_p(z)—

Run the orography check to apply a significant c_o; otherwise c_o = 1.0.

q_p(z) follows UK NA.3a/NA.3b using the live exposure factors. The NA.4a orography bracket is applied only when Module D identifies significant orography and z ≤ 50 m.

Directional Peak Pressure Engine

Directional orography

Governing peak velocity pressure over the 12 wind-from sectors

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Governing direction—

Orography mode—

Orography sectors checked—

Wind FROMdegrees	c_dirNA.1	d_shorekm	d_townkm	c_odirectional	c_eNA.7	c_e,TNA.8	q_pkN/m²

Run the directional engine after calculating the location and shoreline distances.

Town distance is currently treated as uniform in every sector. Quick mode is a screening run: it evaluates orography for the four highest flat-site q_p sectors and assumes c_o = 1.0 elsewhere. Full mode evaluates all 12 SRTM transects sequentially and caches results by location, direction and analysis settings.

Net Pressure & Design Summary

Net pressure coefficient c_p

Design q_p—

Net face pressure w—

Enter the coefficient appropriate to the loaded surface: building face (D + E is commonly about 1.3–1.4), freestanding wall to BS EN 1991-1-4 clause 7.4, clad scaffold to TG20, or the project-specific value. The app does not assume 1.4.

Governing directional wind-design chain

Run directional engine—

Orography Check

Feature type

Wind direction FROM (°N)

Height z above ground (m)

Upwind reach (m)

Wind FROM bearing: 0=N, 90=E, 180=S, 225=SW and 270=W. The app samples an upwind/downwind SRTM transect and detects the effective crest, H and L_u.

Enter inputs and click Check orography.

Shore Distance Method

The entered WGS84 point is compared with every usable segment in the selected Natural Earth coastline dataset. The nearest point on each segment is tested for the overall minimum. Twelve additional rays at 30° intervals are then intersected with the mapped coastline to give the first shoreline crossing in each clockwise direction from north.

Directional Factor

C_dir is taken from Table NA.1 of the UK National Annex to BS EN 1991-1-4:2005+A1:2010. The tabulated directions run from 0° to 330° at 30° intervals, measured clockwise from due north.

Wind Map & Basic Velocity

The supplied Figure NA.1 is displayed as a georeferenced overlay on the interactive map. For Great Britain, the app converts the clicked WGS84 coordinate to the British National Grid and bilinearly interpolates a digitised isopleth surface. Northern Ireland and the Channel Islands use separate approximations because the printed figure contains inset mapping. The result is a map-reading aid: keep the overlay visible and use the manual v_b,map override whenever the original code figure indicates a different value.

Orography Method

The orography check uses an 85-point terrain transect from SRTM 30 m data. The effective crest is taken as the highest sampled point. H, L_u, L_d and the site position relative to the crest are derived automatically before applying the BS EN 1991-1-4 Annex A expressions.

Engineering Limitations

Natural Earth coastline data is suitable for general screening only and is not a legal shoreline, MHWS or flood-boundary dataset. Confirm the terrain profile visually, verify whether the feature is a hill/ridge or cliff/escarpment, and use project-specific survey or authoritative mapping where the result is sensitive.

Click the UK map to select the grid location. Drag the divider to resize the input pane.